While sake is defined as a brewed alcoholic beverage just as wine and beer, its brewing process is more complex.

ln the case of wine, crushed grapes ferment naturally when yeast is added. Similarly, for beer, yeast and warm water are added to crushed malt for fermentation. But, in the case of sake, rice does not begin to ferment by adding yeast only.

Firstly, sake-brewing needs koji-molds which break down rice starch into glucose. (This process is called "saccharification".)
Next, sake yeast is added, and then fermentation start.
This process is called "multiple parallel fermentation" in which saccharification and fermentation occur in the same container at the same time.

This is a unique feature of sake-brewing which cannot be seen in any other brewing processes.

So the use of koji-molds seems critical to sake-making, but what are koji-molds?

Koji-molds are kind of microbes similar to those used in the making of blue cheese, and are good for our health. Soy sauce (shoyu) and soybean paste (miso) are also produced by using as a similar kind of microbe.

What are the main characteristics in the taste of sake?

Due to its longer fermentation process (which can be three or four times that of wine) which produces many types of amino-acids, sake has a balanced and round taste with fresh flavor.

If the brewing process is so complicated, the brewers must be very experienced.

Yes. Since the management of complex sake-brewing requires intuitions as well as specific techniques, all sake makers have their own sake brewery master called the "Toji".

The Toji manages not only the sake-brewing process but also his brewing team including their work-shifts and living arrangements. Maintaining a good team-spirit is important for sake-brewing.

The Toji lives on-site throughout the process, and appoints his successor, passing down his own brewing know-how and techniques.